Presently, the global wireless communication has tended to be more mobile, more broadband and more IP-based, resulting in fierce competitions in the mobile communication industry. For the purpose of a competitive and dominant role in the mobile communication industry, the 3rd Generation Partner Project (3GPP) put forward the Long Term Evolution (LTE) project, an object of which is to achieve a higher data rate, a lower time delay, an improved system capacity and coverage range, and a lower cost.
The transmission mode of data over a wireless link is an important aspect to be focused on to achieve the object of the LTE. In the current LTE solution, the combination of localized transmission and frequency-hopping transmission, instead of the original distributed transmission mode, is used for the transmission of data. The localized transmission is characterized in that the bandwidth used for data transmission is continuous within a certain time period. In the frequency-hopping transmission, a carrier frequency band used for data transmission hops within a range of certain bandwidth, to reduce the impact of fading and homogenize interferences, so that a frequency diversity gain may be obtained. Particularly, a transmission block is transmitted in subframes at different frequency bands during a Transmission Time Interval (TTI).
The LTE is a communication system utilizing a time slot based frame structure, and includes a frequency division duplex mode and a time division duplex mode in terms of a duplex mode. In the time division duplex mode, generally two types of frame structures, i.e. a Generic Frame Structure and an Alternative Frame Structure, may be utilized. The structure of the Generic Frame Structure and the frequency-hopping transmission thereof are described below. FIG. 1 is a schematic diagram illustrating the frame structure of the Generic Frame Structure. As shown in FIG. 1, a wireless frame with a length of 10 ms includes 20 subframes (also referred to as time slots), i.e. subframes #0 to #19 shown in FIG. 1, each having the same length of 0.5 ms, and a TTI of the Generic Frame Structure has a length of 1 ms, which is equal to that of two subframes. Within one TTI, a transmission block is transmitted in two continuous subframes. FIG. 2 is a schematic diagram illustrating the frequency-hopping transmission of the Generic Frame Structure. As shown in FIG. 2, the two subframes are at different frequency bands, particularly, the first subframe is at a frequency band denoted by A, the second subframe is at a frequency band denoted by B, and the first and second subframes are continuous in the frequency domain. Thus, not only requirements of the localized transmission may be satisfied, but also the frequency diversity gain may be obtained.
The frame structure of the Alternative Frame Structure is shown in FIG. 3. As shown, a wireless frame with a length of 10 ms includes two wireless subframes each having a length of 5 ms. Each of the wireless subframes includes 3 special time slots (shown as DwPTS, GP and UpPTS in FIG. 3) and 7 general time slots (e.g. TS0 to TS6 in FIG. 3). The general time slots, each of which has a length of 0.675 ms, are used to for data transmission. A TTI of the Alternative Frame Structure also has a length of 0.675 ms. In this case, a transmission block is transmitted in one time slot of the subframe during the TTI.
Obviously, in the mode of the Alternative Frame Structure, the transmission block is carried by one subframe during the TTI, and it is impossible to obtain a frequency diversity gain since no frequency hopping can be performed for a single subframe in the prior art. Additionally, although the frequency hopping may be implemented between different subframes, because a transmission block within a single TTI is not carried in different subframes, no gain may be obtained for the transmission block through the frequency hopping.